JOSM is an editor for the free map of the world being built at
OpenStreetMap (http://www.openstreetmap.org).  The current version
supports a wide range of graphical editing operations and "pre-sets" for
common objects, and works on stand- alone GPX tracks, GPX track data
from the OSM database and existing nodes, line segments and metadata
tags from the OSM database.

Most of JOSM works nicely on OpenBSD. One exception is the WMS/Yahoo
plugin, which requires a separate executable at present but which should
someday be rewritten to use the Java 2D graphics API.
